Pulsed dye laser fails surgical scars

June 7, 2018

 Pilot study tests whether PDL prior to surgical excision can prevent scarring

Treatment with pulsed dye laser treatment prior to surgical excision does not improve the appearance of surgical scars, according to the results of a pilot study presented at the American Society for Laser Medicine and Surgery annual conference last month in Dallas.

The 595nm pulsed dye laser (PDL) can be used after cutaneous injury to improve the appearance of scars, so researchers wanted to test whether use of PDL prior to surgical excision can prevent scar formation. 

The study included ten patients aged 18 to 65 due to undergo surgical excision for any reason. Immediately before excision, half of each surgical site was treated with a 595nm PDL at varying fluences and pulse durations to achieve an endpoint of transient purpura. The other halves of the sites (controls) received PDL at minimal fluences or were left untreated. Patients and blinded observes were asked to assess the scars at two, four and six weeks, and 8-12 months after the procedure, and digital photographs of the surgical sites were also taken.

There was no clinically significant difference between the treated sites and controls, according to the patient assessment scores at week six (p=0.8798) and month 8-12 (p=0.8773) and the blinded observer assessment scores at week six (p=0.9378) and month 8-12 (p=0.3341).

Although not statistically significant the blinded observers rated the treatment sites worse in appearance than the control sites, whereas patients rated the treatment sites’ appearance as better.  There were no significant adverse events, although three subjects experienced surgical wound dehiscence.

PDL had been expected to change the appearance of the scars based on the theory of selective photothermolysis - that PDL targets oxyhemoglobin the predominant type of hemoglobin present in erythematous and hypertrophic scars - the expectation was that PDL would prevent the formation of excessive vascularisation during the scar formation.
Catherine DiGiorgio, M.D., a fellow in Clinical Laser and Cosmetic Dermatology at Wellman Center for Photomedicine at Massachusetts General Hospital in Boston, told the conference that while the results indicated that laser treatment before the surgeon doesn’t really change the outcome of the scars, the question is why? “Are we limiting the inflammatory response or are we increasing the inflammatory response?” she asked.

She speculated that PDL was increasing the inflammatory response. There wasn’t a significant difference in any of the variables looked at, she pointed out, other than the treatment sites a different color to normal skin when compared with controls.

In terms of the limitations of the study, four patients were lost to follow up, and the majority of the surgical excisions that were performed were performed on the trunk. “We know that excisions performed on that area of the body have poor outcomes to begin with,” DiGiorgio said.


REFERENCE
“Pulsed Dye Laser Treatment Prior to Surgical Excision,” Catherine M. DiGiorgio. American Society for Laser Medicine and Surgery annual conference, Friday, April 13, 2018, Dallas.

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